On turn 117, I made an incorrect move, breaking the chain. On turn 121, because of this, the unit that was supposed to check the consulate had to rush to reconnect the chain to deliver the army to Grisha. And Grisha immediately lost in that unchecked consulate, which turned out to be a maxed-out unit with an upgraded stack.
In hindsight, I realized that the maxed-out unit with an upgraded stack could have been taken, if I had thought a little better and played turns 116-117 differently. I should have taken care of the first speed.